What is it to chase the muffin humes or fumes?

Hi all, well I'm a big fan of Dazed and Confused. There's a scene in the begning when the coach calls the guys over, Benny, Pink, Mel,and Don to talk and ask them if there gonna play football in the fall. Anyway, I was wondering I"m not from the 70's and don't understand all the drug refreneces...and was wondering if anyone knows the movie or knows the term sitting around the pool, chasing the muffin fumes or pshumes??...thanks....